New / improved model parametrizations for responses in phytoplankton growth and calcification to changes in alkalinity implemented

Global biogeochemical ocean models that are currently in place to investigate alkalinity enhancement at a global scale do usually not consider the effects of a changing carbonate system on phytoplankton. We introduce new and modified parameterizations of phytoplankton carbonate systems sensitivities into the biogeochemistry model REcoM. We then compare phytoplankton biomass and net primary production at different atmospheric CO2 concentrations to results from other deliverables (D5.3, 5.6, 5.7) based on experiments and models. The resilience of phytoplankton biomass towards low CO2 concentrations in our model compares well with the results of mesocosm experiments. Or model results differ in the phytoplankton responses compared to the results of a 1D biogeochemical model that employs similar parameterizations regarding the effects on calcifying phytoplankton and total net primary production, which we explain primarily with differences in the spatial scales and phytoplankton communities investigated.